Polymer supported organotin catalyst

ABSTRACT

A tetravalent organotin containing compound where the tin atom is attached via an alkyl group to a phenyl moiety with a polymerizable group thereon, is useful as a monomer. A polymer prepared from the monomer. A transesterification catalyst prepared from the polymer and a process for conducting a transesterification reaction using the transesterification catalyst.

This is a divisional of application Ser. No. 08/254,809, filed Jun. 6,1994, now U.S. Pat. No. 5,436,357.

BACKGROUND OF THE INVENTION

This invention relates to a tetravalent tin containing monomer. Moreparticularly, this invention relates to a monomer as aforesaid, apolymer prepared from said monomer and a catalyst prepared from saidpolymer which is useful for transesterification and a process forconducting a transesterification reaction.

Heterogeneous catalysts are known. They are advantageous when used in atransesterification reaction because the catalyst may easily beseparated from the reaction mixture whereas additional steps arenecessary to separate a homogeneous catalyst from the reaction mixture.

Known polymeric organotin compounds are not effective in catalyzingtransesterification reactions because of their lack of selectivity forthe desired reaction and the fact that the tin tends to leach out tooquickly from the polymer so that only a very few transesterificationreactions may be conducted using a polymeric organotin compound.

Polymeric organotin compounds may be prepared from polymerizable tincontaining monomers.

Known tetravalent tin containing monomers are not suitable for preparingthe transesterification catalysts of this invention because they eitherdo not have the desired functionality for transesterification and themonomer cannot be modified to contain such functionality or thetetravalent tin containing monomer decomposes during polymerization.

It is an object of this invention therefore, to produce a tetravalenttin containing monomer wherein at least one of the ligands is a labilegroup subject to a specific functionalization.

Another object of this invention is to prepare a polymer, from themonomer, which is a useful in preparing a transesterification catalyst.

A further object of this invention is to prepare a transesterificationcatalyst which has a high selectivity, high activity and long catalystlife which may be used in a transesterification reaction.

Yet another object of this invention is to provide a process forconducting a transesterification reaction.

Other objects and advantages will become apparent from the followingmore complete description and claims.

SUMMARY OF THE INVENTION

Broadly, this invention contemplates a composition of matter comprising:##STR1## wherein R₄ is ##STR2## and X is a polymerizable group, n is anumber from 2 to 12;

R₁, R₂ and R₃ are independently selected from the class consisting ofphenyl, allyl, vinyl, naphthyl, alkyl phenyl, (C₁ -C₄) alkyl, (C₁ -C₄)alkylene, alkaryl, aralkyl and R₄ and at least one of R₁, R₂ and R₃ isphenyl, benzyl, allyl or vinyl.

This invention further contemplates a transesterification catalystcomprising:

a polymer having a repeating unit (the term "repeating unit" means atleast two of the units set forth below on the polymer chain) comprising:##STR3## wherein T is ##STR4##

and P is the polymer backbone derived from a polymerizable group, n is anumber from 2 to 12;

S, W and Z are independently selected from a halogen, (such as chloro,bromo, fluoro or iodo), phenyl, allyl, vinyl, naphthyl, alkyl phenyl,(C₁ -C₄)alkyl, (C₁ -C₄)alkylene, alkaryl, aralkyl and alkoxy group andT, and at least one of Z, S or W is an alkoxy group.

This invention also contemplates a process for conducting atransesterification reaction comprising the steps of reacting, at atemperature of from about 50° C. to about 150° C., in the liquid phase,an ester with an alcohol in the presence of a solid polymericheterogeneous tin alkoxide containing catalyst and removing the liquidphase, containing the transesterification product, from theheterogeneous catalyst.

DETAILED DESCRIPTION

The composition of matter, a monomer, is used to prepare the polymerfrom which the transesterification catalyst is prepared and which isused in practicing the process of this invention.

The monomer may be prepared by reacting a tetravalent organotin hydridecompound with a phenyl compound which has a reactive site and apolymerizable group. The reaction is carried out in the presence of acatalyst at an elevated temperature and in an inert atmosphere.

For example, one may react triphenyltin hydride with more than oneequivalent of divinylbenzene in the presence of a catalyst such as2,2-azo-bis-isobutyronitrile at an elevated temperature.

The reaction is considered complete when the tin-hydrogen absorption inthe infrared spectrum at about 1850 cm⁻¹ disappears, for example, aftera period of from about 4 to about 30 hours. The resultant monomer isvinylphenylethyl triphenyltin with divinylbenzene being present. Thereaction results in the saturation of one of the vinyl groups of thedivinylbenzene while leaving a vinyl group attached to the phenyl groupso that the composition of matter is polymerizable.

The reaction is generally conducted in an inert atmosphere, such asnitrogen, at a temperature of from about 20° C. to about 70° C. andpreferably from about 35° C. to about 50° C.

In place of a hydride, which is reacted with the divinylbenzene, toprepare the monomer of this invention, one may use a dihydride and thelike.

The tetravalent tin hydride may be reacted with any compound which willallow the tetravalent tin compound to be linked to a polymerizable groupsuch as a styrenic group. It has been found that crosslinking agents andgraft linking agents are useful in preparing the composition of matterof this invention. For example, in place of divinylbenzene, one may useother polyvinyl compounds which have at least two active vinyl groupssuch as trimethylpropane trimethacrylate, diethylene glycol divinylether, ethylene glycol dimethacrylate, divinyltoluene, trivinylbenzene,divinylchlorobenzene, divinylpyridine, divinylnaphthalene and the like.

It is preferred however to use divinylbenzene as the crosslinking agent.

When preparing the monomer, the tetravalent tin hydride and thecrosslinking or graft linking agent is used in a ratio of one mole oftin hydride to one to four moles of crosslinking or graft linking agent.

Generally, the graft or crosslinking agent is used in excess of thestoichiometric amount required in order to assure that the resultantcomposition will have a polymerizable group thereon, so that the polymermay then be prepared.

In place of the azo-bis-isobutyronitrile catalyst used to prepare themonomer of this invention, one may use any catalyst which is anon-oxidizing free radical initiator. For example, one may use compoundsfrom the azo-nitrile family of compounds such as2,2'-azo-bis-(2,4-dimethylpentane)nitrile; 1,1-azo-bis-cyclohexanenitrile; and other azo derivatives such as 2',2'-azo-bis-isobutane,triazobenzene; and tetrazene compounds such as1,4-dimethyl-1,4-diphenyl-tetrazene-2; and the like.

Thus, one may use any of the foregoing catalysts to conduct the reactionbetween the tetravalent tin hydride and the crosslinking or graftlinking agent.

The polymer is prepared from the monomer composition whose preparationhas been described above.

The polymer of this invention may be prepared from the aforedescribedmonomer by either suspension polymerization, emulsion polymerization,solution polymerization or bulk polymerization.

It is preferred that the polymer be prepared by suspensionpolymerization because beads of a preferred size for conversion to aheterogeneous transesterification catalyst are thereby obtained.

When polymerizing the monomer of this invention, a vinyl-containingcomonomer, may be present. Among such comonomers which may be presentare styrene, divinylbenzene, vinyltoluene, vinylnaphthalene, ethylvinylbenzene, and the like; and acrylates/methacrylates such as ethylacrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, andvinyl acetate, vinyl pyridine and the like.

The amount of vinyl containing comonomer present may vary widely up toabout 95 mole percent of the monomer plus comonomer. It is preferred,however, that if a comonomer is present, it be present in an amount offrom about 30 to about 60 mole percent.

When the polymer is prepared by suspension polymerization, an aqueousdispersion medium is often used. The aqueous phase generally contains adispersant such as xanthan gum (a biosynthetic polysaccharide),poly(diallyldimethyl ammonium chloride), polyacrylic acid and saltsthereof such as the sodium salt, polyacrylarnide, magnesium silicate,hydrolyzed poly(styrene-maleic anhydride) and the like; protectivecolloids such as carboxymethyl cellulose, hydroxyalkyl cellulose, methylcellulose, polyvinyl alcohol, gelatin and the like; buffering agentssuch as phosphate and borate salts and the like; and pH controlchemicals such as sodium hydroxide, sodium carbonate and the Like.

The organic phase generally contains the monomer, comonomer,crosslinking agent, if present, and an initiator and a water immisciblesolvent. The organic phase is slowly added to the aqueous phase. A sweepof nitrogen is initiated over the reaction mixture and gentle stirringis commenced and gradually increased while increasing the reactiontemperature from about 30° C. to about 100° C. The droplet size of themonomer and comonomer to be polymerized is controlled by the rate ofstirring. More rapid stirring tends to favor a smaller droplet size.

When the desired droplet size has been obtained, the temperature isincreased to that needed for polymerization. The droplets turn opaque,indicating that they have polymerized. The polymerization is consideredcomplete when no more opaque beads are formed.

The droplet size, which determines the size of the polymer beads, mayvary widely from about 0.02 mm to about 3.0 mm and preferably from about0.5 mm to about 1.0 mm.

The polymer beads will contain from about 3% to about 30% tin, based onthe weight of polymer, preferably from about 3% to about 15% and morepreferably from about 6% to about 12%.

The transesterification catalyst is prepared from the polymer.

The polymer is suspended in a suitable organic solvent, such astetrahydrofuran. The organic solvent is placed under an inertatmosphere, such as nitrogen and a halogen or a halogenating agent suchas bromine is slowly added to the suspension over a period of time, suchas thirty minutes. The temperature of the suspension is kept below roomtemperature, such as 0° C. in order to assure that the resultanthalogenation reaction is not too vigorous. After the addition of thehalogen is complete, the reaction mixture is stirred for an additionalperiod of time until the halogen is consumed. The resin is thenseparated from the organic medium and dried. The resultant product is apolymeric halogen resin having mono-di or tri halo tin groups.

The halogens and halogenating agents which may be used in preparing thehalogenated resin, which is an intermediate in the preparation of thefinal transesterification catalyst, are fluorine, chlorine, bromine andiodine, hydrogen chloride, hydrogen bromide, tin tetrachloride, and thelike.

If fluorine is to be used, then the reaction vessels which are employedmust be such as to be impervious to the action of fluorine on the wallsof the vessel. If iodine is to be used, then the iodine is dissolved ina suitable solvent, such as tetrahydrofuran, and is used in thereaction.

It is preferred that the halogen or halogenating agent which is to beused is either bromine or hydrogen chloride because they are reactiveand easily handled.

The temperature at which the halogenation reaction is conducted isdependent on the reactivity of the halogen used. For example, if onewere to use fluorine, the reaction would be conducted at a lowertemperature because of the vigorousness of the reaction. However, if onewere to use iodine, then because of the lowered reactivity of theiodine, the reaction may be conducted at a higher temperature.

Generally, the temperature used in conducting the halogenation reactionwill vary from about 0° C. to about 50° C.

The organic medium in which the tin polymer resins are suspended mayvary widely. Generally, any organic .medium may be used which will beinert during the reaction. For example, one may use carbontetrachloride, tetrahydrofuran, chloroform, alkyl or aryl ethers, andthe like.

Prior to converting the halogenated resins to the transesterificationcatalyst, the resin is purified by washing with alcohol, such asmethanol and the like or, tetrahydrofuran, dimethylformamide,dimethylsulfoxide, acetone, methyl ethyl ketone, benzene, toluene,dioxane and the like.

The resin is converted to the alkoxide containing resin by placing asolution of a suitable alkoxide salt in a solvent and adding thehalogenated resins to the solution. The halogenated resins are insuspension in the alkoxide salt solution. The suspension is then heatedto reflux for a period from about 2 hours to about 48 hours under aninert atmosphere such as nitrogen until no further conversion isobtained. The resultant alkoxide resins are then separated and purifiedby an alcohol wash to remove any halogen salts which may be present.

The alkoxides of the following salts may be used in converting thehalogenated resins to the alkoxide resin; lithium, sodium, potassium,ammonium, magnesium, and other alkali or alkaline earth metal salts andthe like.

The alkoxide portion of the salts may vary from a methoxide to a C₂₀alkoxide. It is preferred however, that the alkoxide used be amethoxide, ethoxide or butoxide.

Transesterification using the transesterification catalyst may beaccomplished in the following manner.

An ester and an alcohol may be transesterified using the catalyst andprocess of this invention by reacting the ester with an alcohol in anorganic medium in the presence of the catalyst according to thisinvention.

The ester and alcohol are added to an organic medium. The temperature ofthe transesterification reaction is maintained at from about 50° C. toabout 130° C. for about 0.5 hours to about 8 hours. The reaction isterminated after the desired reaction time has expired or when no morealcohol is produced.

The liquid phase is then decanted and is analyzed by gas chromatography.A fresh charge of ester and alcohol may then be added.

Among the esters which may be used in the transesterification reactionare acetates, methacrylates, acrylates, propionates, butyrates,isobutyrates, fatty acid esters and the like.

The alcohols which may be used generally have from 1 to 30 carbon atoms.Among the alcohols which may be used are: butanol, pentanol, isodecylalcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, and the like.During the reaction, the alcohol formed by the transesterificationreaction is removed by distillation.

In this manner, one may convert methyl isobutyrate and butyl alcohol tobutyl isobutyrate.

Other conversions which may be accomplished using the catalyst andprocess of this invention are methyl methacrylate to: butyl methacrylateor lauryl methacrylate or cetyl methacrylate; ethyl acetate to butylacetate or lauryl acetate or cetyl acetate; and methyl acrylate to butylacrylate; and the like.

The catalyst may be used repeatedly for other transesterifications runswithout significant leaching of the tin from the catalyst or loss ofactivity.

In order to more fully illustrate the nature of this invention and themanner of practicing the same, the following examples are presented.

EXAMPLE 1

Preparation of Monomer-Vinylphenylethyl Triphenyltin DivinylbenzeneMixture

To a 250 ml round bottomed flask equipped with a magnetic stir bar isadded 28.0 grams of triphenyltin hydride, 33.0 grams of 91%divinylbenzene, and 0.26 gram of 2,2'-azo-bis-isobutyronitrile. Themixture is placed under a nitrogen blanket and heated to a temperatureof from 40° to 45° C. Samples of the reaction mixture are periodicallytaken and subjected to infrared analysis. The reaction is terminatedwhen the tin-hydrogen absorption at 1850 cm⁻¹ in the infrared spectrumdisappears. This occurs after approximately 30 hours of heating thereaction mixture. The product is then stored at 0° C. until used for thepreparation of the polymer.

EXAMPLE 2

Preparation of Di(vinylphenylethyl) Di-phenyltin/Divinylbenzene Mixture

The procedure of Example 1 is repeated except that 10.43 grams ofdiphenyltin dihydride, 21.4 grams of 91% divinylbenzene and 0.25 gram ofazo-bis-isobutyronitrile are charged to the flask. The mixture is placedunder a nitrogen blanket and heated as before. Samples are periodicallytaken for infrared analysis. The infrared absorbance for the tin hydride(1850 cm⁻ 1) disappears after about 5 hours. The reaction is terminatedand the product is then stored at 0° C. until it is used.

EXAMPLE 3

Preparation of Tin/Polymer Resin

Preparation of the aqueous phase:

400 Grams of deionized water in a 1 liter four necked round bottom flaskequipped with a condenser, a mechanical stirrer, a bubbler and athermometer is sparged with nitrogen for five minutes to remove theoxygen. Gelatin, 0.60 gram, is then added to the flask and the solutionis stirred at a temperature below 45° C. until the gelatin dissolves.Heating of the solution is discontinued and the solution is allowed tocool. When the temperature of the solution is below 40° C., 14 grams ofpoly(diallyldimethylammonium chloride) are added and the solution isstirred for 15 minutes. Boric acid, 2.0 grams is then added and the pHof the solution is adjusted to about 10 using a 50% sodium hydroxidesolution.

Preparation Of The Organic Phase

To a 500 ml Erlenmeyer flask is added 60.2 grams of thecatalyst/divinylbenzene monomer of Example 1, 30 grams of styrene, 3.0grams of diethylene glycol divinyl ether and 48 grams of4-methyl-2-pentanol as a solvent. The solution is stirred at roomtemperature for about 15 minutes and 2.0 grams of lauroyl peroxide arethen added and the mixture is again stirred until all the peroxidedissolves. The solution is immediately used for the polymerization.

Polymerization

The organic phase is slowly added to the 1 liter reaction flask whichcontains the aqueous phase prepared above. The 2 phases remainseparated. The upper layer is the organic phase. A nitrogen sweep overthe solution is initiated and gentle stirring is commenced. Thepolymerization mixture is maintained at a temperature of about 45° C.The stirring rate is slowly increased to initiate formation of monomerdroplets and to control the droplet size. When the desired droplet sizeis achieved, as determined by visual observation, the temperature isincreased to 75° C. and is maintained at 75° C. overnight. As thepolymerization progresses, the monomer droplets become noticeablyopaque. The polymerization is considered complete when the opaqueness ofthe monomer droplets becomes stable and no longer increases. Heating isthen discontinued and the resultant polymer resin/water mixture isallowed to cool to room temperature. The liquid is decanted and theresins are rinsed with 3 bed volumes of deionized water, extracted withmethanol overnight in a Soxhlet apparatus and vacuum dried at 50° C. Thedry resin is obtained in an amount of 88.2 grams (a 93% polymer yield).The dry polymer resin is represented by the following formula: ##STR5##

Elemental analysis of the resin reveals the following: (percent byweight of the resin) carbon-82.55%; hydrogen-6.99%; and tin-8.82%.

EXAMPLE 4

Preparation of Tin/Polymer Resin

Preparation of the aqueous phase:

The procedure of Example 3 is repeated except that the amounts used areas follows: 150 grams of deionized water; 0.34 gram of gelatin; 7.8grams of poly(diallyl dimethylammonium chloride); and 1.1 grams of boricacid. The pH of the solution is adjusted to about 8 using a 50% sodiumhydroxide solution.

Preparation Of The Organic Phase:

The procedure of Example 3 is repeated except that 30.1 grams of themonomer of Example 2 is used. The amounts of the other components usedare 15 grams of styrene, 1.0 gram of diethylene glycol divinyl ether, 25grams of 4-methyl-2-pentanol, and 0.75 gram of lauroyl peroxide.

Polymerization

The polymerization procedure of Example 3 is repeated. 42.4 grams (92%polymer yield) of dry resin is obtained. The polymer obtained may berepresented by the following formula: ##STR6##

Elemental analysis of the resin reveals the following weightpercentages; 83.53% carbon; 6.89% hydrogen; and 9.01% of tin.

EXAMPLE 5

Preparation of Tin Tribromide Catalyst Intermediate

To a 1 liter, 4-necked round bottom flask equipped with a mechanicalstirrer, a condenser with a bubbler on top, an inlet for addition ofnitrogen and an addition funnel is added 212 ml of tetrahydrofuran and53 grams of tin polymer resin prepared as in Example 3. The suspensionis stirred and cooled to a temperature of 0° C. and placed under anitrogen blanket. Bromine, 30 grams, are added dropwise over a period of30 minutes. After the addition, the flask is wrapped with aluminum foiland the contents of the flask are stirred for an additional six hours atroom temperature. The resin is then separated and extracted in a Soxhletapparatus with a mixture containing 80% tetrahydrofuran and 20%1-decene. The resin is vacuum dried at 50° C. Tin bromide resin beads,54.5 grams, are obtained and are represented by the formula: ##STR7##

The elemental analysis of the resin (percent by weight) is as follows:63.23% carbon; 5.43% hydrogen; 7.12% tin and 22.06% bromine.

EXAMPLE 6

Preparation of Tin Dibromide Catalyst Intermediate

The procedure of Example 5 is repeated except that the tin polymer resinused is that prepared in the manner of Example 4. The amount ofcomponents used are as follows: 40.3 grams of the tin polymer resin; 161ml of tetrahydrofuran; and 14.1 grams of bromine. The resulting tindibromide resin is represented by the following formula: ##STR8##

The elemental analysis of the resin (percent by weight) is as follows:67.97% carbon; 6.45% hydrogen; 5.84% tin; and 17.75% bromine.

EXAMPLE 7

Preparation Of Tin Trimethoxide Polymer Catalyst

A solution of 8.1 grams of sodium methoxide dissolved in 325 ml ofanhydrous methanol and 32.4 grams of the tin tribromide resin of Example5 are added to a 1 liter three neck round bottom flask equipped with amechanical stirrer and a condenser. The suspension is placed under anitrogen blanket and is heated with stirring to reflux for a period of48 hours. The resultant resin is then separated from the liquid and isextracted overnight in a Soxhlet apparatus with methanol and then vacuumdried at 50° C. Tin trimethoxide catalyst resin, (27.9 grams) isobtained and is represented by the formula: ##STR9##

The elemental analysis of the catalyst resin is as follows: 73.11%carbon; 6.57% hydrogen; 8.87% tin; and 5.92% bromine (bromine is presentbecause some bromine has attached itself to the polymer backbone).

EXAMPLE 8

Preparation of Tin Dimethoxide Catalyst Resin

The procedure of Example 7 is repeated except that 7.0 gram of sodiummethoxide, 400 ml of anhydrous methanol and 40 grams of the tindibromide resin of Example 6 are used. Tin dimethoxide catalyst resin(35.9 grams) is obtained and is represented by the formula: ##STR10##

The elemental analysis (percent by weight) of the resin is as follows:75.52% carbon; 6.98% hydrogen; 7.12% tin; and 6.83% bromine.

EXAMPLE 9

Preparation of Tin Bromodimethoxide Catalyst Resin

The procedure of Example 7 is repeated except that 5.6 grams of sodiummethoxide, 740 ml of anhydrous methanol and 74 grams of the tintribromide resin prepared as in Example 5 are used. The tinbromodimethoxide catalyst (62.8 grams) is obtained and is represented bythe following formula: ##STR11##

The elemental analysis (percent by weight) of the catalyst resin is asfollows: 68.88% carbon; 6.43% hydrogen; 8.63% tin; and 12.11% bromine.

EXAMPLE 10

Preparation of Tin Chloro Dimethoxide Catalyst Resin

Tin trimethoxide resin, 17.2 grams prepared as described in Example 7,and 85 ml of anhydrous diethylether are placed into a 500 ml four neckround bottom flask equipped with a mechanical stirrer, a condenser and athermometer. Stirring of the suspension is commenced and 17 ml of a 1.0Msolution of anhydrous hydrogen chloride dissolved in ether is added. Thesuspension is stirred at room temperature for a period of 6 hours. Theresin is then separated, extracted in a Soxhlet using tetrahydrofuranand then vacuum dried at a temperature of 50° C. Tin chlorodimethoxidecatalyst resin, 16.9 grams, is obtained and is represented by theformula: ##STR12##

The elemental analysis of the catalyst resin is 71.94 % carbon; 6.67%hydrogen; 9.89% tin; 2.77% bromine; and 3.53% chlorine.

EXAMPLE 11

Transesterification Process Using A Tin Trimethoxide Catalyst Resin

Methyl isobutyrate, 131 grams, in 19 grams of n-butanol, and 10 grams ofthe tin trimethoxide catalyst prepared as described in Example 7 arecharged to a 250 ml flask equipped with a mechanical stirrer, adistillation column with a distillation head and a thermometer. Themethyl isobutyrate/n-butanol/resin suspension is heated to boiling andthe methanol formed is removed by take off of a methyl alcohol/methylisobutyrate azeotrope. The reaction is terminated after 7 hours. Theliquid phase is then decanted and analyzed by gas chromatography. Afresh charge of methyl isobutyrate/n-butanol is then added to the resinfor another run. A total of 24 runs were conducted with the samecatalyst. For each run, the n-butanol conversion to butyl isobutyrateafter seven hours is given in Table 1 below. Complete conversion may beobtained by extending the reaction time.

                  TABLE 1                                                         ______________________________________                                        CONVERSION OF n-BUTANOL                                                       TO BUTYL ISOBUTYRATE                                                          Run Number   Percent Of Conversion                                            ______________________________________                                         1           92.0                                                              2           57.3                                                              3           50.8                                                              4           44.0                                                              5           37.1                                                              6           43.4                                                              7           41.3                                                              8           42.3                                                              9           40.7                                                             10           36.9                                                             11           35.0                                                             12           35.8                                                             13           40.1                                                             14           43.9                                                             15           39.0                                                             16           29.8                                                             17           29.9                                                             18           33.3                                                             19           36.1                                                             20           34.1                                                             21           32.4                                                             22           32.1                                                             23           34.4                                                             24           35.0                                                             ______________________________________                                    

EXAMPLE 12

Transesterification Reaction Using A Tin Trimethoxide Catalyst Resin

The procedure of Example 11 is repeated except that the followingmaterials are used in place of the materials used in Example 11: 131grams of methyl methacrylate, 19 grams of n-butanol, and 10 grams of thetin trimethoxide catalyst resin prepared as described in Example 7. Thereaction is terminated in 2 hours. The liquid phase is decanted andanalyzed as in Example 11 and a fresh charge of methylmethacrylate/n-butanol is then added to the resins to begin another run.A total of 17 runs were conducted and the n-butanol conversion to butylmethacrylate after 2 hours is given in Table 2. Complete conversion maybe obtained by extending the reaction time.

                  TABLE 2                                                         ______________________________________                                        CONVERSION OF n-BUTANOL                                                       TO BUTYL METHACRYLATE                                                         Run Number   Percent Of Conversion                                            ______________________________________                                         1           98.5                                                              2           83.4                                                              3           63.5                                                              4           55.8                                                              5           54.6                                                              6           59.7                                                              7           54.3                                                              8           58.6                                                              9           49.7                                                             10           50.9                                                             11           54.4                                                             12           49.3                                                             13           52.9                                                             14           49.4                                                             15           50.1                                                             16           47.3                                                             17           47.5                                                             ______________________________________                                    

EXAMPLE 13

Transesterification Reaction Using A Tin Dimethoxide Catalyst

The procedure of Example 12 is repeated except that the catalyst used is10 grams of tin dimethoxide catalyst prepared as described in Example 8.The reaction is terminated in seven hours. The liquid phase is thendecanted and analyzed by gas chromatography. Fresh charges of methylmethacrylate and n-butanol are then added to the catalyst resin to startanother run. A total of 28 runs were conducted with the catalyst and then-butanol conversion to butyl methacrylate after seven hours is given inTable3.

                  TABLE 3                                                         ______________________________________                                        CONVERSION OF n-BUTANOL                                                       TO BUTYL METHACRYLATE                                                         Run Number   Percent Of Conversion                                            ______________________________________                                         1           99.9                                                              2           99.8                                                              3           100.0                                                             4           97.8                                                              5           97.3                                                              6           95.4                                                              7           96.5                                                              8           98.0                                                              9           97.5                                                             10           97.1                                                             11           88.5                                                             12           95.7                                                             13           98.5                                                             14           98.8                                                             15           98.5                                                             16           94.7                                                             17           96.7                                                             18           95.5                                                             19           97.6                                                             20           90.5                                                             21           93.0                                                             22           95.3                                                             23           97.3                                                             24           97.2                                                             25           91.6                                                             26           94.4                                                             27           97.4                                                             28           96.6                                                             ______________________________________                                    

EXAMPLE 14

Transesterification Using A Tin Bromodimethoxide Catalyst

The procedure of Example 12 is repeated except that 10 grams ofpolymeric tin bromo dimethoxide resin, prepared as described in Example9, is used. A total of 17, two hour runs were conducted and then-butanol conversion to butyl methacrylate after 2 hours is given inTable 4.

                  TABLE 4                                                         ______________________________________                                        CONVERSION OF n-BUTANOL                                                       TO BUTYL METHACRYLATE                                                         Run Number   Percent Of Conversion                                            ______________________________________                                        1            98.7                                                             2            98.7                                                             3            97.7                                                             4            94.8                                                             5            93.9                                                             6            93.4                                                             7            92.4                                                             8            89.7                                                             9            91.2                                                             10           90.6                                                             11           82.5                                                             12           82.9                                                             13           Not Measured                                                     14           81.5                                                             15           68.3                                                             16           70.7                                                             17           71.2                                                             ______________________________________                                    

EXAMPLE 15

Transesterification Reaction Using A Tin Chlorodimethoxide PolymerCatalyst

Methyl methacrylate, 73 grams, 27 grams of lauryl alcohol, and 15 gramsof polymeric tin chlorodimethoxide catalyst, prepared as described inExample 10, are charged to a 250 ml flask equipped with a mechanicalstirrer, a distillation column with a distillation head, and athermometer. The methyl methacrylate/lauryl alcohol/catalyst suspensionis heated to boiling and the methanol formed is removed as a methylalcohol/methyl methacrylate azeotrope. The reaction is terminated in 5hours. The liquid phase is then decanted and analyzed by gaschromatography. A fresh charge of methyl methacrylate and lauryl alcoholis added to the resins to start another run. A total of 9 runs wereconducted with the same catalyst and the lauryl alcohol conversion tolauryl methacrylate after 5 hours is given in Table 5.

                  TABLE 5                                                         ______________________________________                                        CONVERSION OF LAURYL ALCOHOL                                                  TO LAURYL METHACRYLATE                                                        Run Number   Percent Of Conversion                                            ______________________________________                                        1            100.0                                                            2            100.0                                                            3            100.0                                                            4            100.0                                                            5            100.0                                                            6             97.7                                                            7             94.1                                                            8             97.2                                                            9             98.7                                                            ______________________________________                                    

While this invention has been described in terms of certain preferredembodiments, and illustrated by means of specific examples, theinvention is not to be construed as limited except as set forth in thefollowing claims:

We claim:
 1. A polymer prepared by polymerizing a compositioncomprising: ##STR13## wherein R₄ is ##STR14## and X is a polymerizablegroup, n is a number from 2 to 12, and R₁, R₂ and R₃ are independentlyselected from the class consisting of phenyl, allyl, vinyl, naphthyl,alkyl phenyl, (C₁ -C₄) alkyl, (C₁ -C₄) alkylene, alkaryl, aralkyl and R₄and at least one of R₁, R₂ and R₃ is phenyl, benzyl, allyl or vinyl. 2.A polymer according to claim 1 wherein said composition isdi(vinylphenylethyl) diphenyl tin.
 3. A polymer according to claim 1wherein said composition is vinylphenylethyl triphenyl tin.
 4. A polymeraccording to claim 1 wherein said composition is vinylphenylethyl butyldiphenyl tin.
 5. A polymer according to claim 1, wherein a comonomer ispresent.
 6. A polymer according to claim 1, wherein a comonomer ispresent and the polymer is crosslinked.
 7. A polymer according to claim6, wherein the polymer has been crosslinked with a crosslinker selectedfrom divinylbenzene, divinyltoluene and diethylene glycol divinyl ether.8. A polymer according to claim 1, wherein tin is present, based on theweight of polymer, in an amount of up to about 30%.
 9. A polymeraccording to claim 1, wherein tin is present, based on the weight ofpolymer, in an amount of from about 3% to about 15%.
 10. A polymeraccording to claim 1, wherein tin is present, based on the weight ofpolymer in an amount of from about 6% to about 12%.
 11. Atransesterification catalyst comprising a polymer having a repeatingunit comprising: ##STR15## wherein T is ##STR16## and P is the polymerbackbone derived from a polymerizable group, n is a number from 2 to12;S, W and Z are independently selected from a halogen, phenyl, allyl,vinyl, naphthyl, alkylphenyl, (C₁ -C₄)alkyl, (C₁ -C₄)alkylene, alkaryl,aralkyl, and alkoxy group and T, and at least one of Z, S or W is analkoxy group.
 12. A transesterification catalyst according to claim 11,wherein n is 2, 10 or
 18. 13. A transesterification catalyst accordingto claim 11, wherein Z is selected from bromo, chloro, fluoro, or iodo.14. A transesterification catalyst according to claim 11, wherein S isselected from phenyl, phenylethyl, vinylphenyl, methoxy or ethoxy.
 15. Atransesterification catalyst according to claim 11, wherein P is derivedfrom a vinyl group.
 16. A transesterification catalyst according toclaim 11, wherein said polymer is crosslinked.
 17. A transesterificationcatalyst according to claim 11, wherein said polymer has beencrosslinked with divinylbenzene.
 18. A transesterification catalystaccording to claim 11, wherein Z is bromo.
 19. A transesterificationcatalyst according to claim 11, wherein Z is chloro.
 20. Atransesterification catalyst according to claim 11, wherein S, Z and Ware methoxy.
 21. A transesterification catalyst according to claim 11,wherein S is bromo, and Z and W are methoxy.
 22. A transesterificationcatalyst according to claim 11, wherein S is chloro and Z and W aremethoxy.
 23. A transesterification catalyst according to claim 11,wherein S and T are the same and Z and W are methoxy groups.